This invention relates to insulating structures in connection with semiconductor junctions, and more particularly, with semiconductor junctions involved in photodetection systems.
Desirably, a photodetection system responding to signals from a photodetector, such as a photodiode, should sense those signals from the photodetector occuring within a selected signal magnitude range, yet be insensitive to detector signals in a smaller magnitude range not representing that which is to be sensed. For sufficiently small values of these smaller magnitude signals in a photodiode, they will at some point be dominated by signal contributions, here signals currents, arising both from unwanted background radiation falling upon the photodetector, and from "dark currents" arising from thermal generation of electron-hole pairs in the depletion or space-charge region of the photodiode. A photodetection system for receiving such photodetector signals should enhance the system response to desired optical signals versus unwanted signals, such as dark currents, by decreasing the system sensitivity at low input signal levels.